Lamp



W; H. WOOD LAMP ori inal Filed Dem-15, 1920 'mwM/vmmc MM M M Patented June I 23, 1925.

UNITED STATES 1,543,141 PATENT OFFICE.

WILLIAM H. WOOD, 0F CLEVELAND, OHIO. I

LAMP.

' Application filed December 13, 1920, Serial No. 430,168. Renewed October 20, 1924.

To all whom it may concern:

Be it known that 1, WILLIAM H. WOOD, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Lamps, of whichects of'the invention are to produce a lamp ulb having therein a simple, compact filamentary arrangement which shall enable the employment either ofa bright light for country driving or a dim light for city driving, both of which shall operate with a maximum etlicienc of illumination and shall both bear suc relation to the reflector as to utilize the largest possible proportion 'of the rays emitted and without causingany objectionable glare. Other objects of the invention are the provision of a dim lighting arrangement which shall maintain uniform the color of the light emitted both under strong lighting and dim lighting conditions; Which shall reduce the current consumption proportionately to the illumination when the dim light is employed and which shall dispense with the necessity of employing a plurality of bulbs inside the reflector; while further objectsvand advantages of the invention will become apparent as the description proceeds.

lit is well known to illuminating engineers that the efficiency of incandescent electric lighting depends largely upon the temperature to which the filament is heated, and that thiseliiciency rises rapidly with an increase of temperature; consequently the use of dimmers which involve the employment of a less highly heated filament is objectione able because of the fact that the decrease of battery energy is not proportional to the decrease in illumination, and the battery is rapidly drained to no good purpose. This 7 is one of the principal reasons which led to the employment of two separate lamp bulbs inside the reflector, both of high efiiciency, but one of them of comparatively to produce only a minimum of beneficial rays. According to my invention I, secure a maximum of efliciency in each filament and furthermore I locate such filaments in such relation to the reflector as to obtain substantially times. In the drawings accompanying and forming a part of this application I have shown certain illustrative embodiments of my invention, but without intent to limit myself thereto further than is specifically set forth in the claims. Fig. 1 is a perspective view of a lamp bulb embodying my improvements; Fig. 2 is a sectional view of a. head equally efiicient use of the same at all light reflector with my improved bulb there in; Fig. 3 IS a diagrammatic view illustrat- 7 ing the electric connections which may be employed inside'one of my improved bulbs, together with a specimen wiring diagram therefor; Fig. 4 is, an enlarged view showing the preferred construction and relation these Vs coincidewith the axis of the reflector in which the same are employed, and their planes are parallel to that axis but angularly related to each other, preferably perpendicular. The two filaments are entirely independent of each other, the apex of one being very slightly displaced longitudinally relative to the other, care being taken to make this as small an amount as is compatible with safety, so as to maintain both the filaments as closely as possible in the focus of the reflector. The apex of the rearmost filament may be madeobtuse if desired to bring it forward. In the present embodiment, 5 re resents thelow-power filament an'd-G' 'the igh-p'o'wer filament, the former being carried by the leading-in wires -5 and 5 and the latter being carried by the leading-in wires 6' and 6*. The base preferably consists of the usual metal shell 2 having therein a plug 10 of insulating material provided with spaced contact blocks 11 and 12 as is customary in all double con- -tact bulbs. One end of each filament is con&

nected to one of these contacts by the leading-wires 5 and 6 the opposite ends of the filaments being grounded upon the shell 2 by the remaining leading-in wires 5", 6". The usual, standard, double-contact socket is employed being grounded to the frame as indicated at 13. One side of the battery 14 is grounded to the frame as shown at 15, and the other side leads to the two switches 16 and 17, each of which is connected to one of the contacts 18 and 19 respectively, located in the receptacle. Upon closing the switch 16 the current flows from the battery through the contacts 18 and 11, through thefilament 5 and back to the battery by Way of the ground 18, thereby affording a dim light; when the switch 17 is closed the current flows from the battery through the contacts 19 and 12 through the filament 6 and back to the battery by way of the ground 18, thereby affording a bright light; these switches being usable separately or simultaneously as desired.

\Vhile it is clear that any type of filaments could be employed herein providing that they possess the relative candle powers described, I prefer the arrangement and construction of filaments shown in Fig. 4: from which it will be seen that each side of the V constituted by the filament 5 consists of a simple, straight, strand of fine resistance wire, while each side of the V which constitutes the high power filament 6 consists of a coarser resistance wire wound into a very small helix. As a result the actual length of wire comprised in the high power filament is greater than that in the low power filament and its concentration within such a small compass causes emission, of a very large quantity of light within this small space, and this at a color and at a current efficiency depending upon the temperature of the wire. The size and resistance of the low-power filament 5 are so chosen as to afford approximately the same temperature and consequently the same color and current efficiency, diminution in the amount of light produced being effected by reason of the less surface area of the filament. The amount of light emitted per square millimeter of wire surface is the same in the two cases, but a different quan-' tity of light is obtained from the two because of the fact that the low power filament is both shorter and smaller.

I do not restrict myself to the use of straight wire for the low-power filament for if desired it also may be coiled as shown at 5 in Fig. 5. Also I do not restrict myself to the use of small loops in such lo-w-power filament but may employ a single large loop 5 just inside the apex of the other filament as shown in Fig. 6. In both modifications it will be seen that the low-power filament is confined substantially to a single plane time with the high-power filament. This proximately with the apex of the high power filament. It will be clear that the low power filament can be so chosen as to afford the same current efliciency inside this single bulb as it could if located in a separate bulb, and that by the herein-described location, it becomes focussed at the same result can be achieved with the use of any of the filaments herein shown, as well as others which will occur to those skilled in the art.

While I prefer to employ my improved k lamps in connection with the reflectors described and claimed in my prior Patent #1,235,27 5, and my prior applications, No. 415,021, filed October 6th, 1920, and No. 417,736, filed October 18, 1920', still I do not restrict myself thereto inasmuch as the same may be employed with any standard automobile head light reflector with or without a special lens and with excellent results. I

do notrestrict myself to the employment of any particular material for such filaments or to the use of filaments of the same material; I do not restrict myself to any special arrangement of leading-in wires or elec. tric connections, -o-r to any other detail except as specified in the claims hereto annexed.

Having thus described my invention, what I claim is:

1. The combination with a reflector having an axis and a focal point, of an incandescent electric light bulb'comprising two independently usable filaments of unequal. candle power, one of the same" being substantially V-shaped with its plane coinciding with the reflector axis and its apex substantially at the focal point, the other filament being located cross-wise of the first filament in the angle made by the legs thereof, the planes of said filaments being substantially perpendicular to each other, the second filament intersecting the axis of the reflector and spaced from the apex of the first filament sufficiently so as not to touch the same and the second filament being shaped to lie substantially within the surface which would be produced by revolving the first filament about the reflector axis.

2. The combination with a reflector having an axis and a focal point, of an incandescent electric light bulb comp-rising two V-shaped filaments arranged with their planes perpendicular to each other and their apices located on the reflector axis substantially at the focal point, said filaments being spaced apart so as not to touch each other, one of the same having each of its legs of wire which is wound in a fine coil, and the other located cross-wise in the angle made 3. The combination with a headlight reflector having an axis and a focal point, of

an electric light bulb comprising two independently usable filaments, each of which is confined to a single plane and inside a triangular space, the planes of said filaments being perpendicular to each other and the vertex of each being located on said axis, the

outer filament consisting of a wire coil whose convolutions lie closely adjacent to each other so as to employ a comparatively large amount of wire, and the inner filament comprising a shorter length of wire having a higher resistance.

4. The combination with a headlight refiector, of an incandescent electric light bulb having therein a high power filament madeof a fine helix of comparatively coarse wire bent in the form of a V, together with a low power filament made of finer wire bentto conform externally approximately to the outline of a V an confined to .a single plane which is perpendicular to the plane of the first V, the apices of both Vs lying on the reflector axis.

In testimony whereof, I hereunto alfix my signature. I

WILLIAM H. WOOD. 

